The point of a slogan is to differentiate your product or brand from that of your competitors, while also underscoring the company's general mission. If you have an advantage over your competitors, or if your product or service has a unique benefit, you need to use it. Slogans are the first impressions for many potential consumers, so it absolutely needs to stress the company's worth. Isolate one key area of your business, and find a way to integrate it into the slogan. Example: "Great taste, less filling." (Miller Lite)

Explain the company's commitment.

Maybe your company doesn't sell a "unique" product or service; nevertheless, the slogan still needs to differentiate the company from other competitors. Often times, winning slogans will explain a company's dedication to its customers. Slogans devoted to customer service, especially ones that guarantee quality and satisfaction even if it's at the company's expense, play extremely well with the public. So if other companies sell the same products as your company does, let them; instead, sell the public on trust and customer care. Example: "We're number two, so we try harder." (Avis)

Keep it short.

Slogans should never be longer than a sentence and ideally should hit the sweet spot between six to eight words. Any longer than a sentence and your slogan will become jumbled and ultimately forgettable, unless it rhymes or has an accompanying jingle. Brevity lends itself to memorability, which is the primary goal with slogan writing, so limit any and all slogans to a sentence or less. Example: "Think different." (Apple)
—Dave Smith

Give them a rhythm, rhyme, and ring.

A slogan longer than a single word should fulfill at least two of these three criteria: It should have a rhythm, it should rhyme, and it should have a ring to it. Slogans, whether read or heard, should be pleasing to the ear; rhythmic and fluid-sounding slogans are much more recognizable and memorable for later recall. Bonus points for making the slogan into a jingle or song; studies consistently show that words presented in a song are remembered significantly better than words presented in normal speech. Example: "The quilted quicker picker upper." (Bounty)

Stay honest.

When writing a slogan, it's extremely easy to get carried away; however, it's imperative that the slogan accurately reflects the business. In other words, hyperbole is extremely discouraged. Language like "The No. 1 ___," or "The best ___ in the business," is not only untrue, but also extremely generic, and a big turn-off to consumers. Instead, be realistic, and find a clever but real way to emphasize your company's perks. Example: "It's everywhere you want to be." (Visa)